How can I make rendering process faster?

Hi, I've noticed that there's pbr2 use another different algorithm, and I have no idea how to make the rendering process faster then it was, could you please show me a way to achieve that? Thanks

No file, test, or entry point is named. Start by locating the pbr2 rendering path and comparing its runtime with the other algorithm mentioned in the issue; define a reproducible performance target and identify the bottleneck before proposing a change. Done should mean a measured rendering improvement with supporting coverage.

Written by the indexing model from the issue text.